Rockwell Automation 1788 NetLinx Media Checker Users Manual - Manual (Page 30)

30 Calculating Trunk, Drop, or Tap Lengths
1788-UM002A-US-P – April 2000
ControlNet Length Calculations
Measured tap lengths depend on whether the taps are terminated or not. See Table 12.
Formulas:
•
Trunk length = Measured length – Total measured length of taps
•
Total tap length = Measured length – Trunk length
Example 1: Calculating trunk length
A cable measures 750 ft long and has 16 unterminated taps.
From Table 12, 16 unterminated taps = 69 measured ft
Trunk length = 750 ft measured length – 69 ft tap length = 681 ft trunk length
Example 2: Calculating total tap length and the number of taps
A cable measures 328 m long. The actual cable length is 274 m. The taps on the cable are terminated.
Measured (terminated) total tap length = 328 m – 274 m = 54 m
From Table 12, 54 meters of terminated taps corresponds to 23 taps.